This invention pertains to conveyor systems, and in particular to those systems which provide a means for physically sorting items placed onto the system.
Conveyor sortation systems are common in the prior art. Conventionally sortation is accomplished by providing a reader to read a preprinted code on an item to be sorted that has been placed onto the conveyor system and thereafter activating an appropriate diverter located in the proximity of the reader to cause the item to be properly sorted. Numerous methods for encoding an item to be sorted have been employed, and items have been encoded not only with visible ink, but also, for example, magnetically. The code may be binary, color, digital, etc. Diverters exist in many forms, and include motor or air-driven cams capable of engaging again and driving the item to be sorted, submerged chain transfer devices that pop up to engage against items to be diverted, similarly acting submerged live roller diverters capable of popping up to engage the items to be diverted, and simple retractable powered pushing devices.
Generally, there are two kinds of limitations on the speed of conventional sortation conveyor systems. First, most diverters require a substantial recovery time to return to the position occupied prior to causing an item to be diverted. That is, the diverters are two-state devices, and after a command to cause a diversion, must take a substantial period of time to return to the original state in which they reposed prior to the command.
The diverter recovery time interacts with a second impediment to high-speed operation of the system, namely, the spacing of items on the system immediately prior to the time the items are subject to diversion. If the items are spaced too closely together, a given diverter may not recover in time to cause an item to be properly diverted. A common means of dealing with this problem has been to slow the conveyor system down to the point that effective diversion becomes possible. To the extent that one seeks to obtain high-speed sortation, one risks in the prior art ineffective sortation, jamming of diverters, and similar problems.